Large Airways Obstruction: Investigation and Treatment

This article should provide an overview of the main type of diseases that affect the lung. You will find a description of the important diagnostic tests used for investigating respiratory diseases, like general principles, emphasis on lung function testing role and interpretation and examples of diagnostic testing approach for some common presentations.

00:00
So what are the clues that
somebody has anobstruction of the trachea or a major bronchi?
Well they'll have obstructive spirometry anda low peak flow, but unlike asthma, it won’t
vary. It's not a reversible cause of airwaysobstruction. The symptoms tend to be positional,
so the patient may lie down and feel worse,or sit back up again and feel better, whereas
in asthma it would be diurnal. The patientis worse at night, coughs in the morning,
but is better in the evening. In large areasobstruction, the wheeze is usually inspiratory.
Stridor rather than inspiratory which is thewheeze that you might get with asthma or COPD.
There may be a history that explains the potentialcause for large airways obstruction or a history
of prolonged intubation for whatever reasonin the past suggesting there may be a tracheal
stenosis. The flow volume loop is very helpful,because that can show a very characteristic
change that you get with large airways obstructionwith flattening of the inspiratory and expiratory
flow volume loops, and that's shown in thisdiagram on the right hand side of the slide.
But obviously you need to do a flow volumeloop to see this appearance, and most patients
presenting with cough and airways obstructionmay not get a flow volume loop. So again, that
comes back to the high index of suspicion.
01:20
If somebody may have large airways obstruction,
do a flow volume loop. Another clue is that thepeak flow falls in a greater way relative
than the FEV1, and that's because the peakflow is largely dependent on flow down the
larger airways, whereas FEV1 is largely dependenton flow down the smaller airways. So the peak
flow will be very low, and the FEV1 may bequite low but not nearly as low as you might
expect for how low the peak flow is. How doyou investigate these patients? Well, peak
flow, lung function tests, flow volume loopas already discussed. X rays of the chest to
the neck can show changes as the mediastinaltumor, there may be mediastinal mass invisible
for example. But the important investigationis the CT scan, that's the definitive X ray and
that should show where there's a mass obstructingthe larger airways and you can see an example
here of a CT scan where somebody with a verylarge mediastinal tumor, that's the sort of
heterogeneous grey mass in the middle of thex-ray and the trachea has a very small slit
like object pointed to by number 1. And youcan see that there's both displaced and very
narrow compared to its normal position.
02:31
And if somebody has that sort of appearance or
you suspect they have large airways obstruction,then the test you need is a bronchoscopy,
because you can visually see the obstruction,and then you can also do biopsies to identify
the cause of that obstruction although youhave to bear in mind that that can be dangerous
because the patient may bleed, and the extrablood on top of the obstruction may precipitate an
acute large airways obstruction. And bronchoscopycan be used for treatment, as we will discuss
in the next slide or two. So, somebody presentingwith acute large airways obstruction that is a
medical emergency. Obstructing the tracheacan kill you very easily. So sit the patient
up, they feel better when they are sittingup. Give them high flow oxygen, and sometimes
we give them what we call heliox, and that'sa 50/50 mixture of oxygen and helium and that
causes the viscosity of the inhaled gas tobe lower and that can get past obstruction
more easily than normal air. We give patientshigh dose intravenous corticosteroids as a
stat dose and follow that by continued intravenousdoses or oral prednisolone depending on how
unwell the patient is, and we do that becausethere may be surrounding oedema of the cause
of obstruction.
03:51
So if you have tumor, as it grows it causes
oedema around the surrounding tissue and thatoedema can be reduced by steroids, and that
makes a substantial difference to the actualobstruction to the airway. So the high dose
steroids are very useful. We used nebulizedbronchodilators, salbutamol and in fact we
use adrenaline as well. Intravenous fluidreplacement is necessary, these patients are
often breathing fast and are dehydrated asa consequence. And these patients do need
to be considered for free potential lifesavinginterventions. One, they may need intubation.
Now clearly, putting an ET tube (endotrachealtube) down somebody with a tracheal obstruction
is difficult and requires specific skillsbecause there will be a tight trachea and
that will require a small tube to get pastthat. A tracheostomy is very beneficial as long
as the obstruction is above the tracheostomysite, so that would be the high trachea or the
larynx. And then patients may need bronchscopicintervention. That is not a treatment for very
acute obstruction but if people are presentingwith semi-acute and you have the time to arrange
a bronchscopic intervention, then that maybe very beneficial. Chronic treatment. So
somebody has an airway obstruction, it's beenidentified by peak flow and flow volume loop
and a bronchoscopy, how do you get past thatobstruction, how do you sort it out? Well, it
depends on the cause. Somebody has a cancer,then you would use radiotherapy, potentially
to improve that. There is also a variety ofbronchoscopic interventions that can be used
to get past large airways obstruction and theseinclude laser ablation over tumors eroding
into the trachea for example, or you couldput stents across tight areas, which will
open up and push the stenosis away. And then,surgery could be considered. That could remove
the cause of the tumor for example, especiallythe benign tumors of the trachea. And then
tracheostomy could be a long term way of avoidingchronic obstruction, but again that has to
be a high airways obstruction somewhere upin the upper trachea or the larynx.

About the Lecture

The lecture Large Airways Obstruction: Investigation and Treatment by Jeremy Brown, PhD is from the course Airway Diseases.

Included Quiz Questions

The following would suggest asthma rather than large airways obstruction:

Fall in home peak flow readings after an upper respiratory tract infection.

Only a very limited improvement in low peak flow recordings with treatment.

Positional wheeze and stridor.

Squared off’ flow volume loop appearance

Which of the following is NOT a feature of large airway obstruction?

Expiratory stridor.

"Squared off" flow volume loop.

A fall in PEFR relatively more than the FEV1

Positional variation of the symptoms.

Minimal variability of the peak flow.

A mother who is a nurse by profession notices her two-year-old child having difficulty breathing with inspiratory stridor and fever since 1 week. She notices that he is drooling saliva and she examines the child's throat. She sees kissing tonsils. What is the next best step?

Admission into paediatric care facility since its a medical emergency.

Provide antibiotics for the treatment.

Observe the child over the days and look for improvement.

Keep the child hydrated and give Tylenol.

Do chest X-ray to rule out lower respiratory tract infection.

Which of the following is NOT a part of the treatment plan in acute obstruction of the large airways?

Spirometric assessment to decipher the type obstructive process.

Make the patient sit up with Heliox mixture given via mask.

Intravenous high dose corticosteroids.

Nebulised salbutamol and adrenaline.

Urgent bronchoscopic intervention / intubation or tracheostomy.

Which of the following is NOT used as a management choice of large airway obstruction?

Bronchoalveolar lavage.

Bronchoscopy.

MRI.

CT scan.

Tracheostomy.

Author of lecture Large Airways Obstruction: Investigation and Treatment

Jeremy Brown, PhD

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